1. Field of the Invention
The present invention relates to an anti-skid braking control system for use in a motor vehicle, and more particularly to an anti-skid braking control system having a brake master cylinder, a wheel brake actuating cylinder on a wheel, a braking fluid pressure circuit interconnecting the brake master cylinder and the wheel brake actuating cylinder, an actuator disposed in the braking fluid pressure circuit for controlling braking fluid pressure therein, a fluid pressure pump for generating a power fluid pressure to be supplied to the actuator, and a power fluid pressure supply and discharge valve for supplying and discharging the power fluid pressure to and from the actuator depending on a skidding condition of the vehicle. The anti-skid braking control system operates, when the brakes are actuated and when any one of the wheels of the vehicle is about to be locked, to reduce the braking fluid pressure in the wheel brake actuating cylinder by increasing the volume of the braking fluid pressure circuit, thus preventing the wheel from being locked and the vehicle from skidding.
2. Description of the Prior Art
One anti-skid braking control system is disclosed in Japanese Patent Publication No. 58-199258. The disclosed anti-skid braking control system includes a cylinder body having a first cylinder accommodating therein a piston for increasing and reducing the volume of a braking fluid pressure circuit leading from a brake master cylinder, to a wheel brake actuating cylinder a first valve for cutting off the braking fluid pressure circuit in response to operation of the piston, and a second valve disposed in a second cylinder defined in the cylinder body parallel to the first cylinder for providing fluid communication between the brake master cylinder and the wheel brake actuating cylinder in bypassing relation to the first valve.
The first and second cylinders are independently defined in the cylinder body with no parts being shared thereby, and hence the cylinder assembly is relatively large in size. Since the first and second cylinders are parallel to each other, fluid communication between the brake master cylinder and the wheel brake actuating cylinder through the second valve has been required to be made through a passage defined between the first and second cylinders remotely from the outer surface of the cylinder body.